The present invention relates to servo defect compensating operation of an optical disc drive, and more particularly, to a method of servo defect compensation for a scratch disc and a related optical disc drive system with a digital signal processor (DSP).
In a conventional optical disc drive comprising an optical pick-up unit for reading an optical medium having defects such as a scratch, there is no defect compensation scheme when the optical pick-up unit passes through the defect. The focusing and tracking servo is in a close loop control while reading data from the optical medium, and after the optical pick-up unit passes through the defect, the focusing and tracking servo will probably point at somewhere far from the desired focus/tracking point due to factors such as spindle rotating speed, clamp direction, size of the defect, defect detect level, and digital equalizer design. The focusing and tracking servo traces back using a larger transient response, but the RF quality of data read from the optical medium is typically deteriorated. This issue becomes more serious in high resolution discs such as Blu-ray